As shown in FIGS. 1 and 2 of the state of the art, an aircraft's floor, which is pressurized and deformable, is currently known to be used at the level of the central wing section. The main function of the pressurized floor (1) is to ensure water tightness between the cabin area, situated above the floor, and the outside, and to support force situated above said floor.
Said floor (1) includes a succession of lengthwise beams (2), parallel to the lengthwise axis of the aircraft. The lengthwise beams (2) are fixed on the front end at the center wing partition and on the back end at the vertical watertight bulkhead of the aircraft, Front or back should be understood in relation to the direction of advance of the aircraft into which the floor is intended to be installed. The curved membranes (3), which are flexible and watertight, extend between the lengthwise beams (2) so as to form a pressurized partition. Only the external lengthwise beams, bordering the side walls (4) of the fuselage, are interlocked with the aircraft, and more specifically, said side walls (4) of said fuselage. The side walls (4) of the fuselage are understood to be the right and left walls of said fuselage. The lengthwise beams (2) and the curved membranes (3) are covered by the panels (5) forming the surface to which the passenger seats and/or the articles are fixed. The curved membranes (3) and the center lengthwise beams, i.e., float and extend between the two external lengthwise beams, which allow the floor (1) to adapt to the deformations imposed by the aircraft structure while in flight, while ensuring water tightness between the cabin area and the exterior.
FIG. 3 shows a schematic cross-section view of a segment of the fuselage at the level of the wing partition (7) when the aircraft is in flight.
Under the force of compression and traction which are applied to the wing (6), the underside curve (8) of said wing (6) elongates while the outer curve (9) of said wing shortens, imposing a similar deformation in the center partition of the wing (7) and of the floor (1) situated above said wing partition (7). More precisely, the floor (1) bends.
In addition, the floor (1) undergoes deformations at the back and on its side edges due to lateral flexing and twisting of the back fuselage under the forces resulting from drift. However, the section of aircraft's fuselage provided with a state of the art pressurized floor (1) has a cross section which may be considered an open section (FIG. 2), because of the flexibility of said pressurized floor (1). Such a floor (1) is not suitable for transferring certain forces to which the fuselage is subjected in flight, and in particular horizontal shear flow, which is due to the twisting of the fuselage and the lateral shear force. The transfer of the force is only assured by the side areas of the pressurized floor, attached to the side walls of the fuselage.
The state of the art pressurized floor (1) undergoes repeated duress during the aircraft cycles, which entail fatigue fissures at the level of the curved membranes (3). The fissures on the level of the connections between the curved membranes (3) and the lengthwise beams (2) are propagated and grow larger, requiring the partial or total replacement of the curved membranes (3).